You could bring a lot to this group if perhaps you did not talk down to us. We have nothing to prove and we are here to share.

RELEASE us from your Holier-than-thou CONTROL attitude

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Not trying to belittle anyone. Guess I'm trying to gain trust and respect too soon too early. Being support for small, medium & large landscape service contractors for over 14 years trying to position myself as their goto guy for helping to resolve service issues, save accounts etc.. Didn't mean to give the wrong impression. Will try to fix the perception.Posted via Mobile Device

Ok I will try to clarify. The atrazine label says not to spray over certain temps. They say its too hot and it will burn. I understand they are covering their liabilities. I have sprayed atrazine in 102 temps. No damage to follow because I took into consideration the turfgrass conditions. Very healthy and strong. No problem for atrazine. Now it wasn't off label at that temp just off suggestion. I would not spray within 25 feet of the mean water line. That's off label. If the label says I can't, I don't. If it says I shouldn't because of risk. I'll make that call on my experience. Not the label. I still have no trouble killing dollarweed new or older with atrazine.Posted via Mobile Device

Ok I will try to clarify. The atrazine label says not to spray over certain temps. They say its too hot and it will burn. I understand they are covering their liabilities. I have sprayed atrazine in 102 temps. No damage to follow because I took into consideration the turfgrass conditions. Very healthy and strong. No problem for atrazine. Now it wasn't off label at that temp just off suggestion. I would not spray within 25 feet of the mean water line. That's off label. If the label says I can't, I don't. If it says I shouldn't because of risk. I'll make that call on my experience. Not the label. I still have no trouble killing dollarweed new or older with atrazine.Posted via Mobile Device

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Well they are correct; it has nothing to do with liabilities as opposed to a scientific certainty borne out of experience in product trials.

To recommend applying Atrazine or virtually any broad leaf herbicide @ temps approaching 102, and assuming the turf is "healthy enough" to tolerate it (specially without having been out to the site) is wildly speculative and irresponsible!

Even applying Celcius or Metsulfuron (noted for minimal stress to St. Augustine turf at higher temperatures) at temperatures approaching 100 is at the very least unwise if not just plain stupid.

Explain how or why atrazine would burn please. I am just curious. What is atrazines mode of action. Posted via Mobile Device

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Atrazine inhibits photosynthesis; like all triazenine class of herbicides, it interferes with electron transport during photosynthesis and eventually leads to cell membrane destruction and cellular leakage.

Floratam, the most common St. Augustine cultivar in my area is tolerant of atrazine herbicides when temperatures are below 85°F.

The label clearly states:

"Do not apply when temperatures exceed 90o F. Use only on healthy turf grass which is not under heat or drought stress and reasonably free of infestations of insects, nematodes, and diseases. Use in the United States should be confined to Southeastern States only. Applications during the summer should be limited to spot treatment only."

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In general, Atrazine results are inconsistent. Different St. Augustine cultivars have different tolerence levels, Floratam being the most tolerant. One cannot assume that an incidence of an application being well tolerated by a cultivar @102 degress indicates it is always appropriate to apply it under those conditions. Reasonable men would act on the side of prudence in it's application.

I would like to hear from others that they had sucess with Atrazine above 90 degrees without incuring damage to St. Augustine.

Atrazine inhibits photosynthesis; like all triazenine class of herbicides, it interferes with electron transport during photosynthesis and eventually leads to cell membrane destruction and cellular leakage.

Floratam, the most common St. Augustine cultivar in my area is tolerant of atrazine herbicides when temperatures are below 85°F.

The label clearly states:

Atrazines mode of action to my knowledge is growth accelerator. Growing weeds through their life cycle at a speeded rate. That's why most applicators and homeowners notice the weeds get "bigger "after a couple of weeks. Atrazine takes about 3 to 4 weeks to complete this process. Thats why sometimes some weeds die some look yellow and some look fine. Different weed species different results. Short life cycle weeds easy to kill one app longer life cycle ones harder. That can be seen in medium size dollarweed. Sometimes after 4 week cycle its just bigger. A follow up app insurers this process finishes the weed life cycle. Another reason follow up apps are more important than 1st apps sometimes.

In general, Atrazine results are inconsistent. Different St. Augustine cultivars have different tolerence levels, Floratam being the most tolerant. One cannot assume that an incidence of an application being well tolerated by a cultivar @102 degress indicates it is always appropriate to apply it under those conditions. Reasonable men would act on the side of prudence in it's application.

I would like to hear from others that they had sucess with Atrazine above 90 degrees without incuring damage to St. Augustine.

Better go back to school; no-one has disagreed with me yet. When they do... I'll admit applying Atrazine @ 102f is a good idea.

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No need for school. It's funny you say that. When I was a LESCO associate. The hort professor at velencia college used to have me come by to discuss turfgrass science as a guest speaker in his class when he was covering pesticide use because of my ability to metaphor it to be easy understood . PS. He also took notes. Again, as I've been told on this forum that I talk down to everyone. I guess I have used poor choices in words, marking myself a jerk. Again 14 years using pesticides to 13 years selling and studying them. I believe I have a fair grasp on proper application technique. Just because you don't know it yet does not make it untrue. I've even picked up dimes from the floors of random customers warehouses... with their forklift...just to win a
friendly bet.

Maybe their are tricks I know that you do not and vice versa. The point is. I hope not to show the same disregard of someones experiences since its something they did vs something they read.Posted via Mobile Device